How to Preserve Postman Iteration Data Order

I am creating an iteration data in the next form:

[{
    "F": {
       "a": "1",
       "b": "2"
    },
    "C": {
       "a": "4",
       "b": "3"
    },
    "A": {
       "a": "6",
       "b": "2"
    }
}]

When I read the pm.iterationData in Postman, it shows the array in the next form:

[{
    "A": {
       "a": "6",
       "b": "2"
    },
    "C": {
       "a": "4",
       "b": "3"
    },
    "F": {
       "a": "1",
       "b": "2"
    }
}]

I would like to preserve the original order. How I can do that in Postman?